Tube bender



Feb- 12, 1963 G. E. FRANCK ETAL 3,077,221

Filed Aug. 28, 1961 20 t' @eofgeEj-v'nc/Q 3 Charleljlowe,

3,077,2Zl Patented Feb. l2, i963 3,077,221 TUBE BENDER George E. Franck, Morton Grove, and Charles L. Rowe, Lake Forest, Ill., assignors to Imperial-Eastman Corporation, a corporation of Illinois Filed Aug. 28, 1961, Ser. No. 134,402 9 Claims. (Cl. 153-46) This invention relates to tube working tools and in particular to manually operable tube bending tools. In one well-known construction of manually operable tube bending tools, a mandrel is provided with a tube bending peripheral groove generated about an axis. The groove is arranged to receive the tube during the bending operation, the tube being pressed into the groove by means of a bending shoe provided with a tube pressing surface. Conventionally, the bending shoe is moved along the groove with the tube pressing surface thereof confronting the groove. To maintain the shoe in the desired confronting relationship juxtaposed to the mandrel groove, the shoe conventionally is connected to the mandrel by a suitable connector. The present invention comprehends such a tube bender having a new and im proved connecting means which positively retains the shoe in the desired arcuate path adjacently along the mandrel groove while permitting a desired spacing of the shoe from the mandrel periphery at a single preselected portion of the groove to permit facilitated installation and removal of the tube in and from the space between the mandrel groove and pressing surface of the shoe.

Thus, a principal object of the present invention is to provide a new and improved tube bender structure.

Another object of the invention is to provide such a tube bender structure comprising new and improved means for connecting the shoe and mandrel element-s thereof.

A further object of the invention is to provide such a tube bender structure having new and improved means for permitting spacing of the shoe from the mandrel groove at a single preselected portion of the groove and arranged to retain the shoe in juxtaposed confronting relationship to the groove at all other portions thereof. Still another object of the invention is to provide such a tube bender structure wherein the connecting means comprises a post on the mandrel projecting axially therefrom and having a wedge-shaped cross section comprising a portion of a circle defined by allochiral converging chords and 4diametrically opposed long and short arcs, and a connector having a first portion fixed to the shoe and4 a second portion provided with a slot for extensiontherethrough of the post, said slot having a cross section comprising a circular portion having a diameter substantially equal to the diameter of the post defined by the arcs and a trapezoidal portion extending radially from the circular portion and having radially outwardly converging side surfaces corresponding to the chords, whereby the connector may be disposed with the post extending selectively through the circular portion or through the trapezoidal portion of the slot.

Other features and advantages of the invention will be apparent from the following description, taken in connection with the accompanying drawing wherein:

FIG. 1 is a fragmentary elevation of a tube bender provided with connecting means embodying the invention, with a tube portion associated therewith as at the initiation of a tube bending operation;

FIG. 2 is a fragmentary elevation similar to that of FIG. 1 but with the shoe juxtaposed to the mandrel in a tube bending position;

FIG. 3 is a fragmentary elevation similar to that of FIG. 2 but with the shoe positioned as subsequent to the completion of a 90 bend in the tube;

FIG. 4 is a fragmentary elevation similar to that of FIG. 3 but with the shoe positioned as upon completion of a 180 bend in the tube; and

FIG. 5 is a fragmentary enlarged section taken substantially along the line 5 5 of FIG. 3.

In the exemplary embodiment of the invention as disclosed in the drawing, a tube bender generally designated 10 is shown to comprise a mandrel 11 and a shoe 12 movably associated wtih the mandrel by means of a connector 13. Herein, the connector is integrally associated with the shoe; the connector, however, may comprise a separate element tixedly secured to the shoe by suitable means.

The mandrel 11 is provided with a peripheral segmentally annular groove 14 generated about an axis 15 of the mandrel and arranged to receive the tube T during the tube bending operation. As best seen in FIGS. l and 5, the mandrel comprises a generally cylindrical member having a chordal surface 16 at opposite ends of the groove 14. A conventional tube holding hook 17 may be secured to the mandrel at surface 16 by suitable means such as screw 18. A handle 19 may be secured to the mandrel 11 and a handle 20 may be secured to the shoe 12 for manipulation of the shoe 12 to eifect the desired bend in the tube T.

As best seen in FIG. 5, connector 13 comprises a at element pivotally juxtaposed to one surface 21 of the mandrel 11 by means of a stepped cylindrical post 22 projecting coaxially from the mandrel and provided at its opposite ends with enlarged heads 23 and 24 retaining the connector 13 and handle 19 respectively in association with the mandrel. The post includes ailatted cylindrical mid portion 25 retained against rotation about axis 15 in a corresponding ilatted cylindrical hole 26 extending axially through the mandrel 11. Adjacent enlarged head 24, the post is provided with a portion 27 extending through the handle 19 for fixing the handle 19 against rotation about the axis of the post. Between mid-portion 25 and enlarged head 23, the post is provided with a portion 28 having a wedge-shaped cross section and extending through a slot 29 in the connector 13.

Referring now more speciiically to FIG. 1, slot 29 comprises a keyhole-shaped slot having a circular portion 30 and a generally trapezoidal portion 31 extending radially from the circular portion. The cross section of post portion 28 comprises a portion of a circle dened by allochiral converging chords 32, a short arc 33, and a long arc 3d. As shown in FIG. 1, the arcuate length of arc 34 is greater than the corresponding arcuate distance be- `tween the side surfaces 35 of the trapezoidal portion 31 of the slot 29 at the juncture thereof with the circular portion Sil. As best seen in FIG. 2, the arcuate length of the short are 33 is shorter than the corresponding arcuate distance between the side surfaces 35 at the juncture thereof with the circular portion 3d. As may be seen in FIG. 1, the radial length of the trapezoidal portion 31 is substantially less than the diameter of the post 22 defined by the arcs 33 and 3K3. The radially outer end of the trapezoidal portion 31 may be arcuate generally similar to the arcuate portion 33 of the post so that, as shown in FIG. 1, the post effectively bottoms thereon when received fully in the trapezoidal portion of the slot, The side surfaces 32 of the post and the side surfaces 35 of the slot are arranged to converge at similar angles. Thus, when the post is so disposed in slot portion 31, the side surfaces 32 of the post facially engage the side surfaces 35 of the slot portion 31. Herein, the side surfaces 32 and the side surfaces 35 respectively converge at the included angle of approximately 8.

The invention further comprehends the arrangement of the trapezoidal portion 31 of slot 29' so as to receive the post portion 28 only when the shoe is arranged with serveer its tubefpressing surface 37 disposed at a preselected starting portion 33 of groove 1li. in the illustrate-d embodiment, the diameter of slot portion 3d bisecting the trape- Zoidal portion 3l extends through the bend starting portion 33 and, thus, is perpendicular to the pressing surface 37 when the pressing surface is disposed at -bend starting portion 33.

To facilitate the desired bending of tube T, the mandrel li may be provided with conventional peripheral angle markings 39 and the connector i3 may be provided with a sight hole 40 through which the markings 39 may be viewed. Thus, as shown in FIG. 2, when the shoe is at the bend starting position, the zero degree marking is observable through the opening di). Other angles of disposition of the sho-e relative to the bend starting position may similarly be determined by observation of the markings 39 through the opening itl in the various positions of the shoe.

The use of tube bender 1t) is seen by consecutive consideration of FIGS. 1-4. Thus, in FIG. l, the tube bender is arranged so that the shoe 12 is spaced from the mandrel sufficiently to allow lready insertion of the tube T between the shoe surface 37 and the mandrel groove 14. To permit this spacing, the connector 13 is arranged so as to receive the post portion 23 within the trapezoidal portion 31 of the slot 29 with the arcuate portion 33 of the post bottoming on the radially outer surface 36 of the slot.

To dispose the shoe 12 in position for the beginning of the bend, the shoe is then moved toward the mandrel until the connector 13 is redisposed so as to have post portion 28 disposed fully within the circular portion 30 of the slot. Suitable manipulation of handle may then be effected to move the shoe circumferentially along the peripheral groove 14 from the position of FIG. 2 to the position of FIG. 3. During this movement, the arcuate surfaces 33 and 34 of the post have sliding facial engagement with the cylindrical surface of the slot 29 positively retaining the shoe surface 37 juxtaposed t-o the mandrel periphery for proper bending of the tube T into the groove 14.

Referring now to FlG. 4, the manipulation of shoe 12 may be continued, if desired, until the shoe is redisposed approximately 180 from the bend starting position 'whereby the tube Tis bent int-o a U-shaped configuration. .As the arcuate surface 34tof the post now confronts the trapezoidal portion 3i of the slot, and as the length of the :arcuate surface 34 is substantially greater than the cor- :responding arcuate spacing between the slot surfaces 35 'at the juncture thereof with the circular portion 30, the post is positively prevented from entering the trapezoidal portion 3l. Thus, the post is effectively precluded from 4catching or hanging up and a simple foolproof manipula- :tion of the tube bender is assured.

To release the bent tube, the handle 253` is manipulated to return the shoe l2 back to the starting position of FIG. 2 whereupon the post is once again aligned with ,the trapezo-idal portion 31 of the slot so as to permit the ready movement of the shoe outwardly from the position lof FIG. 2 to the position of lG. l. A s the shoe is then substantially spaced from the mandrel, the bent tube may be removed from the mandrel groove as desired. Tube bender l@ is then ready for a subsequent bending operation similarly as discussed above.

As a substantial surface enagement occurs between the post and the circular portion of the mandrel slot at all times during the bending operation, improved troublefree life of the bending tool is obtained. Further, the connection between the mandrel and the shoe is extremely rugged so as to assure maintained alignment of the shoe surface 37 relative to the groove lo at all times. Further, the simple structure of the connecting means effectively minimizes the cost of the bending tool while effectively maximizing etiiciency and facility of operation.

While we have shown and described one embodiment ,of our invention, it is to be understood that it is capable ea of many modifications. Changes, therefore, in construeF tion and arrangement may be made without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

l. in a tube bender having a mandrel provided with a tube-bending peripheral groove generated about an axis, and a bending shoe provided with a tube-pressing surface for urging a tube portion into the mandrel groove for conformation therewith, means for selectively retaining the shoe for movement along the tube-bending groove with the tube-pressing surface closely adjacent thereto and for spacing the shoe substantially from the tube-bending groove at a single preselected portion of the groove comprising: a post on the mandrel projecting axially therefrom, said post having a wedge-shaped cross .section comprising a portion of a circle defined by allochiral converging chords and diametrically opposed long and short arcs; and a connector having a first portion fixed to the shoe, and a second portion provided with a slot for extension therethrough of said post, said slot having a cross section comprising a circular portion having a diameter substantially equal to the diameter of the post defined by said arcs, and a trapezoidal portion extending radially from the circular portion and having radially outwardly converging side surfaces cor responding to said chords, whereby said connector may be disposed with said post extending selectively through said circular portion or through said trapezoidal portion.

2. The tube bender means of claim 1 wherein said post includes enlarged end portions retaining the post against substantial axial movement in said mandrel.

3. The tube bender means of claim l wherein said long are is longer than the corresponding arcuate distance between said side surfaces of the trapezoidal portion of the slot at the juncture thereof with said circular portion of the slot.

4. The tube bender means of claim 1 wherein the radial length of said trapezoidal portion is substantialiy less than the diameter of the post defined by .said arcs.

5. The tube bender means of claim 1 wherein the trapezoidal portion of the slot includes a radially outer arcuate end surface substantially similar to the portion of the post defined by said short arc whereby the post may be bottomed on said end surface with the portion of the post defined by said chords facially engaging said side surfaces of the slot.

6. The tube bender means of claim l wherein said -glords converge at an included angle of approximately 7. in a tube bender having a, mandrel provided with a tube-bending peripheral groove generated about an axis, and a bending shoe provided with a tube-pressing surface for urging a tube portion into the mandrel groove for conformation therewith, means for selectively retaining the shoe for movement along the tube-bending groove with the tube-pressing surface closely adjacent thereto and for spacing the shoe substantially from the tube-bending groove at a preselected bendstart portion of the groove comprising: a cylindrical post on the mandrel projecting axially therefrom, said post having a wedge-shaped cross section comprising a portion or" a circle defined by allochiral converging chords and diametrically opposed long and short arcs, the center of said arcs being disposed on a diameter of said axis extending through the bend-start portion of the mandrel groove; and a connector having a first portion fixed to the shoe, and a second portion provided with a slot for extension therethrough of said post, said slot having a cross section comprising a circular portion having a diameter substantially equal to the diameter of the post defined by said arcs, and a trapezoidal portion extending radial-ly from the circular portion and away from said circular portion and having converging side surfaces corresponding to said chords, whereby said connector may be disposed selectively with `said post extending selectively through said circular portion or through said trapezoidal portion.

3. The tube bender means of claim 7 wherein said first portion of the connector is fixed to the shoe to have said tube-pressing surface extend substantially perpendicular to a diameter of said circular portion of the slot bisecting said trapezoidal portion thereof.

9. The tube bender means of claim 7 wherein the radial length of said trapezoidal portion of the slot is 5 greater than the diameter of the tube to be bent.

No references cited. 

1. IN A TUBE BENDER HAVING A MANDREL PROVIDED WITH A TUBE-BENDING PERIPHERAL GROOVE GENERATED ABOUT AN AXIS, AND A BENDING SHOE PROVIDED WITH A TUBE-PRESSING SURFACE FOR URGING A TUBE PORTION INTO THE MANDREL GROOVE FOR CONFORMATION THEREWITH, MEANS FOR SELECTIVELY RETAINING THE SHOE FOR MOVEMENT ALONG THE TUBE-BENDING GROOVE WITH THE TUBE-PRESSING SURFACE CLOSELY ADJACENT THERETO AND FOR SPACING THE SHOE SUBSTANTIALLY FROM THE TUBE-BENDING GROOVE AT A SINGLE PRESELECTED PORTION OF THE GROOVE COMPRISING: A POST ON THE MANDREL PROJECTING AXIALLY THEREFROM, SAID POST HAVING A WEDGE-SHAPED CROSS SECTION COMPRISING A PORTION OF A CIRCLE DEFINED BY ALLOCHIRAL CONVERGING CHORDS AND DIAMETRICALLY OPPOSED LONG AND SHORT ARCS; AND A CONNECTOR HAVING A FIRST PORTION FIXED TO THE SHOE, AND A SECOND PORTION PROVIDED WITH A SLOT FOR EXTENSION THERETHROUGH OF SAID POST, SAID SLOT HAVING A CROSS SECTION COMPRISING A CIRCULAR PORTION HAVING A DIAMETER SUBSTANTIALLY EQUAL TO THE DIAMETER OF THE POST DEFINED BY SAID ARCS, AND A TRAPEZOIDAL PORTION EXTENDING RADIALLY FROM THE CIRCULAR PORTION AND HAVING RADIALLY OUTWARDLY CONVERGING SIDE SURFACES CORRESPONDING TO SAID CHORDS, WHEREBY SAID CONNECTOR MAY BE DISPOSED WITH SAID POST EXTENDING SELECTIVELY THROUGH SAID CIRCULAR PORTION OR THROUGH SAID TRAPEZOIDAL PORTION. 